This is an interesting "myth," because depending on how you look at it, it can be considered a true or false statement. In school you probably learned that the colors of the rainbow are (in order) red, orange, yellow, green, blue, indigo and violet. These are actually the colors of the visible spectrum. Red has the longest wavelength and violet the shortest. (Some scientists think indigo is so similar to blue that it's indistinguishable for most people [source: National Geographic].) But those seven hues are not the only ones in the world, of course. Where's the pink, for example? Or brown? Or sage, aqua, celadon and coral?
Those colors, and more, are actually there in the rainbow. They're just invisible. Rainbows contain upward of 1 million colors – that's right, 1 million – in a much larger continuum than the seven measly ones with which we're familiar [source: Howard]. Unfortunately, our human peepers can't see all of those other hues. So does this mean rainbows contain them or not? That's for you to debate.